1. Field of the Invention
The present invention relates to a solid-state image sensor and a camera including it.
2. Description of the Related Art
In a solid-state image sensor disclosed in Japanese Patent Laid-Open No. 2012-84815, protruded portions made of a light reflecting member are arranged at boundary portions between adjacent pixels on a semiconductor substrate in order to reduce mixture of colors, and an insulating film is formed to cover the protruded portions. In the insulating film, steps generated by the protruded portions are reflected to form concave lenses. The concave lens can condense incident light to a photoelectric converter. The protruded portions have a lattice shape in which rectangular openings are two-dimensionally arrayed.
In the solid-state image sensor disclosed in Japanese Patent Laid-Open No. 2012-84815, the concave lens formed by the insulating film has a shape conforming to the rectangular opening at the protruded portion. The concave lens may actually have a shape in which a truncated pyramid-like hole is formed in the insulating film. For this reason, the light collection effect may change depending on the incident direction of a beam to the concave lens. For example, in FIG. 5, a light collection effect obtained when a beam enters the concave lens parallel to the side of the rectangular opening, as indicated by an arrow A, differs from a light collection effect obtained when a beam enters the concave lens in the diagonal direction of the rectangular opening, as indicated by an arrow B. This may cause nonuniformity of sensitivity in the image sensing region and nonuniformity of the effect of reducing mixture of colors.